The Iosif Vissarionovich tank (or IS tank, also known as the Joseph Stalin tank), was a heavy tank developed by the Soviet Union during World War II and first used in the Kursk area in September 1943. The tanks in the series are also sometimes called JS tanks.

The heavy tank was designed with thick armour to counter the German 88 mm guns, and carried a main gun that was capable of defeating the German Tiger and Panther tanks. It was mainly a breakthrough tank, firing a heavy high-explosive shell that was useful against entrenchments and bunkers. The IS-2 was put into service in April 1944, and was used as a spearhead in the Battle of Berlin by the Red Army in the final stage of the war.

Two candidate weapons were the A-19 122 mm gun and the BS-3 100 mm gun. The BS-3 had superior armour penetration (185 mm compared to 160 mm), but a less useful high explosive round. Also, the BS-3 was a relatively new weapon in short supply, while there was excess production capacity for the A-19 and its ammunition. Compared to the older 76.2 mm tank gun, the A-19 had very good armour penetration, similar to that of the effective 75 mm high velocity gun mounted on the German Panther, and delivered 3.5 times the kinetic energy of the older F-34.

The separate shells and charges of the two-piece ammunition of the A-19/D-25T 122mm gun. Left to right: the cartridge, high-explosive/fragmentation shell PF-471, armor-piercing tracer shell BR-471, armor-piercing capped shell BR-471B. All shells are shown from two sides.

After testing with both BS-3 and A-19 guns, the latter was selected as the main armament of the new tank, primarily because of its ready availability and the effect of its large high-explosive shell when attacking German fortifications. The A-19 used a separate shell and powder charge, resulting in a lower rate of fire and reduced ammunition capacity, both serious disadvantages in tank-to-tank engagements. However, the gun was very powerful, and while its 122 mm armour-piercing shell had a lower muzzle velocity than similar late-issue German 75 mm and 88 mm guns, Soviet proving-ground tests established that the A-19 could penetrate the front armour of the German Panther tank, and it was therefore considered adequate in the anti-tank role.

Pictured here is a 1:72 scale diecast replica of a Russian JS-2 heavy tank that saw action at Vitebsk, Russia, during the winter of 1944. Now in stock!

Historical Account: "Returning the Favor" - By the summer of 1944, Army Group Centre's northern flank was defended by the Third Panzer Army under the command of Georg-Hans Reinhardt; the lines ran through marshy terrain in the north, through a salient round the city of Vitebsk, to a sector north of the main Moscow-Minsk road, held by the Fourth Army. It was opposed by the 1st Baltic Front of Hovhannes Bagramyan, and Chernyakhovsky's 3rd Belorussian Front, who were given the task of breaking through the defenses to the north and south of Vitebsk and cutting off the salient.

It was in this sector that Soviet forces had their greatest initial gains. The Soviet 43rd Army broke the defences of the German IX Corps, to the north of Vitebsk, within hours, pushing towards the Dvina river. South of the city, the VI Corps' 299th and 197th Infantry Divisions simply disappeared beneath an overwhelming Soviet assault, with a particularly effective breakthrough by the 5th Army at the junction of the 299th and 256th Infantry Divisions' sectors. By June 24th, the German position in Vitebsk itself, held by the central LIII Corps of four divisions, was already serious, as Soviet forces were clearly intending to encircle the city, but no reserves were available to shore up the collapsing defences, and requests to withdraw German troops to the second defense lines, the 'Tiger' line, were denied by the Oberkommando des Heeres.

By June 25th, Third Panzer Army was disintegrating. In the north, IX Corps had been broken and pushed over the Dvina, blowing the bridges during its retreat. In the south much of the VI Corps had been annihilated, and its southernmost divisions (the 299th and 256.Infanterie Divisions) had become separated from the remainder of Third Panzer Army by heavy attacks around Bogushevsk, where they attempted to make a final stand in the 'Hessen' line, the third defense zone. The Soviet 43rd and 39th Armies were now converging behind Vitebsk, trapping the entire LIII Corps. LIII Corps' commander, Friedrich Gollwitzer, had transferred the 4th Luftwaffe Field Division south-west of the city in order to spearhead a breakout, while the 246.Infanterie Division attempted to hold open the Dvina crossings. OKH however, denied all requests for complete evacuation: the 206.Infanterie Division was ordered to stay in the city and fight to the last man.

Soviet plans in this sector met with overwhelming success. The 4.Luftwaffe Field Division was cut off and destroyed by the 39th Army on the evening of June 25th, and by the next day the 246.Infanterie and 6th Luftwaffe Field Divisions, fighting their way along the road from Vitebsk, had also been encircled. Hitler insisted that a staff officer be parachuted into Vitebsk to remind Gollwitzer that the trapped 206.Infanterie Division should not withdraw; Third Panzer Army's commander, Reinhardt, was only able to get this decision reversed by insisting on being parachuted in himself if Hitler continued to order it. By the evening Soviet forces were fighting their way into the city and Gollwitzer finally ordered the garrison to withdraw too, in defiance of Oberkommando des Heeres (OKH) orders.

By June 27th, LIII Corps had been dispersed, its 30,000 men being almost all killed or taken prisoner; a group of several thousand from the 4th Luftwaffe Field Division initially managed to break out, but was liquidated in the forests west of Vitebsk] The remnants of IX Corps were retreating to the west, falling back on Polotsk with the 6th Guards Army in pursuit: VI Corps was also largely destroyed. Third Panzer Army had been effectively shattered within days, and Vitebsk liberated: even more significantly, a huge gap had been torn in the German lines to the north of Fourth Army in the former VI Corps sector.